Use copy_file_range to copy files
The copy_file_range syscall (introduced in Linux kernel version 4.5) can copy files more efficiently via server-side copy etc. * admin/merge-gnulib (GNULIB_MODULES): Add copy-file-range. * lib/copy-file-range.c, m4/copy-file-range.m4: New files, copied from Gnulib. * lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate. * src/fileio.c (Fcopy_file): Try copy_file_range first, falling back on read+write only if copy_file_range failed or if the input is empty and so could be a /proc file.
This commit is contained in:
Paul Eggert
parent
111408a0e9
commit
486a81f387
6 changed files with 123 additions and 9 deletions
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@ -27,7 +27,7 @@ GNULIB_URL=git://git.savannah.gnu.org/gnulib.git
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GNULIB_MODULES='
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alloca-opt binary-io byteswap c-ctype c-strcase
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careadlinkat close-stream
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careadlinkat close-stream copy-file-range
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count-leading-zeros count-one-bits count-trailing-zeros
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crypto/md5-buffer crypto/sha1-buffer crypto/sha256-buffer crypto/sha512-buffer
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d-type diffseq dosname dtoastr dtotimespec dup2
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33
lib/copy-file-range.c
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33
lib/copy-file-range.c
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@ -0,0 +1,33 @@
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/* Stub for copy_file_range
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Copyright 2019 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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#include <config.h>
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#include <unistd.h>
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#include <errno.h>
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ssize_t
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copy_file_range (int infd, off_t *pinoff,
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int outfd, off_t *poutoff,
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size_t length, unsigned int flags)
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{
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/* There is little need to emulate copy_file_range with read+write,
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since programs that use copy_file_range must fall back on
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read+write anyway. */
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errno = ENOSYS;
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return -1;
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}
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@ -74,6 +74,7 @@
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# c-strcase \
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# careadlinkat \
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# close-stream \
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# copy-file-range \
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# count-leading-zeros \
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# count-one-bits \
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# count-trailing-zeros \
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@ -1274,6 +1275,17 @@ EXTRA_DIST += close-stream.h
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endif
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## end gnulib module close-stream
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## begin gnulib module copy-file-range
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ifeq (,$(OMIT_GNULIB_MODULE_copy-file-range))
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EXTRA_DIST += copy-file-range.c
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EXTRA_libgnu_a_SOURCES += copy-file-range.c
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endif
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## end gnulib module copy-file-range
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## begin gnulib module count-leading-zeros
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ifeq (,$(OMIT_GNULIB_MODULE_count-leading-zeros))
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36
m4/copy-file-range.m4
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36
m4/copy-file-range.m4
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@ -0,0 +1,36 @@
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# copy-file-range.m4
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dnl Copyright 2019 Free Software Foundation, Inc.
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dnl This file is free software; the Free Software Foundation
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dnl gives unlimited permission to copy and/or distribute it,
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dnl with or without modifications, as long as this notice is preserved.
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AC_DEFUN([gl_FUNC_COPY_FILE_RANGE],
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[
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AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
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dnl Persuade glibc <unistd.h> to declare copy_file_range.
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AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
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dnl Use AC_LINK_IFELSE, rather than AC_CHECK_FUNCS or a variant,
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dnl since we don't want AC_CHECK_FUNCS's checks for glibc stubs.
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dnl Programs that use copy_file_range must fall back on read+write
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dnl anyway, and there's little point to substituting the Gnulib stub
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dnl for a glibc stub.
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AC_CACHE_CHECK([for copy_file_range], [gl_cv_func_copy_file_range],
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[AC_LINK_IFELSE(
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[AC_LANG_PROGRAM(
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[[#include <unistd.h>
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]],
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[[ssize_t (*func) (int, off_t *, int, off_t, size_t, unsigned)
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= copy_file_range;
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return func (0, 0, 0, 0, 0, 0) & 127;
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]])
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],
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[gl_cv_func_copy_file_range=yes],
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[gl_cv_func_copy_file_range=no])
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])
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if test "$gl_cv_func_copy_file_range" != yes; then
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HAVE_COPY_FILE_RANGE=0
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fi
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])
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@ -56,6 +56,7 @@ AC_DEFUN([gl_EARLY],
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# Code from module clock-time:
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# Code from module cloexec:
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# Code from module close-stream:
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# Code from module copy-file-range:
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# Code from module count-leading-zeros:
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# Code from module count-one-bits:
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# Code from module count-trailing-zeros:
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@ -201,6 +202,11 @@ AC_DEFUN([gl_INIT],
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AC_CHECK_FUNCS_ONCE([readlinkat])
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gl_CLOCK_TIME
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gl_MODULE_INDICATOR([close-stream])
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gl_FUNC_COPY_FILE_RANGE
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if test $HAVE_COPY_FILE_RANGE = 0; then
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AC_LIBOBJ([copy-file-range])
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fi
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gl_UNISTD_MODULE_INDICATOR([copy-file-range])
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gl_COUNT_LEADING_ZEROS
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gl_COUNT_ONE_BITS
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gl_COUNT_TRAILING_ZEROS
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@ -846,6 +852,7 @@ AC_DEFUN([gl_FILE_LIST], [
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lib/cloexec.h
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lib/close-stream.c
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lib/close-stream.h
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lib/copy-file-range.c
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lib/count-leading-zeros.c
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lib/count-leading-zeros.h
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lib/count-one-bits.c
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@ -995,6 +1002,7 @@ AC_DEFUN([gl_FILE_LIST], [
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m4/builtin-expect.m4
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m4/byteswap.m4
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m4/clock_time.m4
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m4/copy-file-range.m4
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m4/count-leading-zeros.m4
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m4/count-one-bits.m4
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m4/count-trailing-zeros.m4
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41
src/fileio.c
41
src/fileio.c
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@ -2117,14 +2117,39 @@ permissions. */)
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newsize = st.st_size;
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else
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{
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char buf[MAX_ALLOCA];
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ptrdiff_t n;
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for (newsize = 0; 0 < (n = emacs_read_quit (ifd, buf, sizeof buf));
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newsize += n)
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if (emacs_write_quit (ofd, buf, n) != n)
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report_file_error ("Write error", newname);
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if (n < 0)
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report_file_error ("Read error", file);
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off_t insize = st.st_size;
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ssize_t copied;
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for (newsize = 0; newsize < insize; newsize += copied)
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{
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/* Copy at most COPY_MAX bytes at a time; this is min
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(PTRDIFF_MAX, SIZE_MAX) truncated to a value that is
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surely aligned well. */
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ptrdiff_t copy_max = min (PTRDIFF_MAX, SIZE_MAX) >> 30 << 30;
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off_t intail = insize - newsize;
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ptrdiff_t len = min (intail, copy_max);
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copied = copy_file_range (ifd, NULL, ofd, NULL, len, 0);
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if (copied <= 0)
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break;
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maybe_quit ();
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}
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/* Fall back on read+write if copy_file_range failed, or if the
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input is empty and so could be a /proc file. read+write will
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either succeed, or report an error more precisely than
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copy_file_range would. */
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if (newsize != insize || insize == 0)
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{
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char buf[MAX_ALLOCA];
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for (; (copied = emacs_read_quit (ifd, buf, sizeof buf));
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newsize += copied)
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{
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if (copied < 0)
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report_file_error ("Read error", file);
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if (emacs_write_quit (ofd, buf, copied) != copied)
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report_file_error ("Write error", newname);
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}
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}
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}
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/* Truncate any existing output file after writing the data. This
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